Question

9(a^2+1)^2- 4(b^2-1)^2​

Answer 1

$9( {a}^{2} + 1) {}^{2} - 4( {b}^{2} - 1) {}^{2}$

$= 9( {a}^{4} + 1) - 4( {b}^{4} + 1)$

$= {9a}^{4} + 9 - {4b}^{4} - 4$

$= {9a}^{4} - {4b}^{4} + (9 - 4)$

$= {9a}^{4} - {4b}^{4} + 5$